(
2005-07-31)
Cook, Mea S.; Keigwin, Lloyd D.; Sancetta, Constance A.
The lithology of deglacial sediments from the Bering Sea includes intervals of laminated
or dysaerobic sediments. These intervals are contemporaneous with the occurrence
of laminated sediments from the California margin and Gulf of California,
which suggests widespread low-oxygen conditions at intermediate depths in the
North Pacific Ocean. The cause could be reduced intermediate water ventilation,
increased organic carbon
flux, or a combination of the two. We infer abrupt decreases
of planktonic foraminifer δ18O at 14,400 y BP and 11,650 y BP, which may
be a combination of both freshening and warming. On the Shirshov Ridge, the abundance
of sea-ice diatoms of the genus Nitzschia reach local maxima twice during the
deglaciation, the latter of which may be an expression of the Younger Dryas. These
findings expand the extent of the expression of deglacial millennial-scale climate
events to include the northernmost Pacific.
